This invention relates to a device for identifying a circumferential position on a non-vertical pipe. More particularly, the invention relates to a device for accurately and reproducibly identifying a particular point on the circumference of a non-vertical pipe for use as a reference mark for pipe inspections.
Various types of mechanical equipment may be designed to revolve about a non-vertical pipe. A typical example is an optical scanner used to examine pipes and pipe welds for structural integrity. Such scanners are useful in environments such as chemical process plants or nuclear reactors, where the structural integrity of pipes and pipe welds must be monitored periodically and reproducibly.
Such revolving scanners have been developed. One problem associated with these devices is that the operator must be able to accurately determine the circumferential position of the scanner in order to relate the optical data generated to the proper physical location on the pipe. In particular, it would be desirable to accurately identify a single point as a reference mark to ensure reproducibility during subsequent service inspections. Ideally, such identification should not require a physical mark or change on the surface of the pipe being inspected.